Multistory steel-framed buildings have conventionally been constructed using vertical steel columns spanning the full height of the building from the bottom floor to the roof. Each column is often provided in one piece for buildings with only a few stories. For buildings with more than a few stories, each column is commonly constructed from multiple column members, each spanning several floors. After placement of the columns, floors are then framed with horizontal beams attached to the columns by fin plates or welding, and joists and floor decking are installed on the horizontal beams.
In prior designs, the vertical columns can be relatively tall. In some cases, columns may extend 30 to 50 feet or more for a structure having only a few floors. Because the columns are so tall, they are necessarily very heavy. A steel column for a typical three-story building may have a weight in the range of about 700 to 1,200 pounds. As a result, heavy-duty lifting equipment is generally required to place the columns in position. Cranes must often be stationed on the construction site, which adds significant cost and potential coordination difficulties to the project.